U.S. patent number 7,727,259 [Application Number 11/044,268] was granted by the patent office on 2010-06-01 for bio-flexible spinal fixation apparatus with shape memory alloy.
Invention is credited to Kyung-Woo Park.
United States Patent |
7,727,259 |
Park |
June 1, 2010 |
Bio-flexible spinal fixation apparatus with shape memory alloy
Abstract
The present invention relates to a spinal fixation apparatus
having a segment flexible rod for connecting pedicle screws and a
transverse link for spacing out the rods, which are made from a
shape memory alloy, thereby easily and simply connecting the rods
and the pedicle screws. According to the present invention, it can
easily and simply fit the rods to the misaligned pedicle screw,
even if it may be a failure of alignment of the pedicle screws in
surgery. Also, it can easily set up the transverse link on a pair
of the longitudinal rods, even if the longitudinal rods are
declined or are not in parallel.
Inventors: |
Park; Kyung-Woo (Kangnam-Gu,
Seoul 135-283, KR) |
Family
ID: |
36075050 |
Appl.
No.: |
11/044,268 |
Filed: |
January 28, 2005 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20060064090 A1 |
Mar 23, 2006 |
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Foreign Application Priority Data
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Sep 22, 2004 [KR] |
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10-2004-0076105 |
Sep 22, 2004 [KR] |
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10-2004-0076106 |
Nov 26, 2004 [KR] |
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10-2004-0097833 |
Nov 26, 2004 [KR] |
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10-2004-0097834 |
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Current U.S.
Class: |
606/255 |
Current CPC
Class: |
A61B
17/7052 (20130101); A61B 17/7005 (20130101); A61B
17/7007 (20130101); A61B 17/7008 (20130101); A61B
17/7026 (20130101); A61B 2017/0645 (20130101); A61B
17/7004 (20130101); A61B 17/7032 (20130101); A61B
17/7028 (20130101); A61B 17/7011 (20130101); A61B
2017/00867 (20130101) |
Current International
Class: |
A61B
17/70 (20060101) |
Field of
Search: |
;606/61,78,254,255,257,264,265,267,271,272 ;623/17.13
;403/197,206,208,212,213,231,240,241,244,245,246 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2 846 223 |
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Apr 2004 |
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FR |
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04-244149 |
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Jan 1992 |
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JP |
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07-255759 |
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Sep 1995 |
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JP |
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2003529415 |
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Oct 2003 |
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JP |
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2000-0011302 |
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Jun 2000 |
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KR |
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20-0250854 |
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Oct 2001 |
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KR |
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20-0338006 |
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Dec 2003 |
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KR |
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WO 02/085217 |
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Oct 2002 |
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WO |
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WO 02/102259 |
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Dec 2002 |
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WO |
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WO02/102259 |
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Dec 2002 |
|
WO |
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WO 03/039330 |
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May 2003 |
|
WO |
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WO 03/094692 |
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Nov 2003 |
|
WO |
|
Other References
Supplementary European Search Report dated Nov. 19, 2008 for
European Application No. EP 04 80 8432. cited by other.
|
Primary Examiner: Robert; Eduardo C
Assistant Examiner: Fisher; Elana B
Attorney, Agent or Firm: Collard & Roe, PC
Claims
What is claimed is:
1. A spinal fixation apparatus comprising: a plurality of pedicle
screws, each of which has a head formed at a top portion thereof
and a thread formed below the head to be implanted into a pedicle
of a vertebra, wherein the head has a reception cavity and two
parallel rod grooves in a bottom surface of the reception cavity; a
rod connected to a first pedicle screw and a second pedicle screw
of said plurality of pedicle screws for preventing a movement of
the vertebra, wherein said rod is made of a shape memory alloy
which can be transformed at a designated temperature and wherein
said each rod includes: 1) a straight bar placed in line with a
center of the heads of said first and second pedicle screws of said
plurality of pedicle screws; 2) an elastic section formed in the
straight bar; and 3) a first support bar disposed at a first end of
said rod and a second support bar disposed at a second end of said
rod, opposite said first end, said first support bar having a first
bending portion extending from a first end of the straight bar and
bent along a first outer surface of the head of said first pedicle
screw, said second support bar having a second bending portion
extending from a second end of the straight bar and bent along a
second outer surface of the head of said second pedicle screw, said
first support bar further having a first line portion extending
from said first bending portion, and said second support bar
further having a second line portion extending from said second
bending portion, wherein said first support bar is received in a
first rod groove of said two parallel rod grooves associated with
said head of said first pedicle screw of said plurality of pedicle
screws and said second support bar is received in a second rod
groove of said two parallel rod grooves associated with said head
of said second pedicle screw of said plurality of pedicle screws,
and a plurality of set members, each of said plurality of set
members being inserted into a respective reception cavity of the
head of a respective pedicle screw of said plurality of pedicle
screws for preventing a movement of said rod.
2. The spinal fixation apparatus according to claim 1, wherein said
rod is in a martensite phase at a temperature of approximately
+10.degree. C. and below and is in an austenite phase at a
temperature of approximately +35.degree. C. and over.
3. The spinal fixation apparatus according to claim 1, wherein said
elastic section of said rod has a coil spring shape.
4. The spinal fixation apparatus according to claim 1, further
comprising a plurality of head caps, each of said plurality of head
caps being joined to the head of a respective pedicle screw of said
plurality of pedicle screws.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a spinal fixation apparatus which
can correct and immobilize injured or deformed human spine; and,
more particularly, to a spine fixation apparatus for easily
carrying out an operation on the spine, by using segment flexible
rods and a transverse link which are made from a shape memory
alloy, so that the rod and the transverse link can elongate in
different shapes with flexibility.
2. Description of the Related Art
Typically, the vertebra typically consists of 24 bones (except for
sacral vertebra). They are connected to each other through joint
segments and there are discs between the joint segments. By this
structure, the vertebra has man's posture kept and a shock
absorbed. Also, the vertebra is essential to exercises and protects
all internal organs from an external shock. However, the vertebra
of the spine can be injured or wrenched by external environments,
abnormal postures for a long time and anaplastia and so on, which
may induce a serious back pain by pressing the nerve system passing
through the spine.
Patients, who have been injured in a part of his spine, cannot take
their activities in daily life, because the injured part of the
spine is compressed by adjacent other parts of the spine. This
spinal disorder requires a surgical intervention to treat the pain
which is induced in nerve root by the compression and unstableness
of intervertebral joints.
As shown in FIG. 1, a conventional spinal fixation apparatus
includes a plurality of pedicle screws 200 which are respectively
inserted through the pedicle into injured or deformed vertebra,
wherein each of the pedicle screws 200 has a head 201 formed at a
top portion thereof, wherein the head 201 has a U-shaped rod
passage 201a and a female thread 201b is formed on an inner surface
thereof, and wherein a thread 202 is formed below the head 201 in
order that the pedicle screws 200 can be implanted into the
vertebra; a pair of longitudinal rods 250 which are located in both
laterals of the spine and coupled to the pedicle screws 200 for
preventing a movement of the vertebra; a number of set screws 300,
each of which has a male thread and a wrench hole 300a on an upper
surface thereof, being inserted into the rod passage 201a of the
head 201 of the pedicle screw 200 for preventing a movement of the
rod; and a transverse link 400 for holding the longitudinal rods
250.
In the conventional spinal fixation apparatus, the rods and the
pedicle screws will be described in short, referring to the
accompanying drawing.
As shown in FIG. 2, the thread 202 of the pedicle screws 200 is
implanted into the vertebral body 500. The rod 250 is then put into
the rod passage 201a. In this situation, the set screw 300 is
joined to the female thread 201b of the rod passage 201a.
Also, the set screw 300 is joined to the rod passage 201a, by
inserting it into a groove 300a and turning it with a wrench on the
top thereof. As a result, the bottom side of the set screw 300
compresses the top of the rod 250 within the rod passage 201a of
the pedicle screws 200.
According to this assembly, the rod 250 is definitely tightened up
on the pedicle screw 200 to correct the diseased or injured
vertebral body 500. The both ends of the transverse link 400 are
coupled to the pair of the rods 250 so that the transverse link 400
is laid across the rods 250 which is connected to the pedicle
screws 200. When a patient gets to do a wrenched action toward his
left or right sides, the transverse link 400 prevents a rotation
and migration of the rod 250.
In the conventional spinal fixation apparatus, the rod 250
functions as a basic element to correct the vertebra. Therefore,
the material of the rods or the properties of the rod, such as
elasticity, has a large effect on human body, after it is
inseparably fused together with the vertebra. The rod 250 itself is
not elastic because it is made from a titan alloy for medicine. It
is very difficult to keep the line of his lumber normal since the
vertebra segment is fused together with the rod to correct the
vertebra bodies.
Also, after the vertebra is integrally fused together with the rod,
the weight is concentrated upon the upper segment or the lower
segment so that it will cause another vertebra stegnotic or
instability of a lumbar vertebra within a few years after the
vertebra fusion.
In particular, it has some problems in that the rod can be broken
and buried in the vertebra, when a shock is inflicted upon the
lumbar vertebra.
The rod is made to have a normal spinal curvature shape without
being related to a specific spinal shape of individual. That causes
the difficulty of standardizing each single products and making
various shapes, thereby increasing the cost of products. Also, the
rod structure induces a series of bottlenecks in connecting the
pedicle screw to the rod because the rod has a straight shape. That
is, the individual spinal shape is different from each other.
Therefore, if the pedicle screws are not fixed uniformly between
the segments, it was very difficult to install the straight rod on
the pedicle screws. This is caused by the physical properties of
the rod. In this case, an operator has to adjust a distance and
direction of the pedicle screw based on the location of the rod, by
making the pedicle screw slanted. Also, the operator has to adjust
an angle of the pedicle screw's head, using the polyaxial type
screw, which can freely rotate a head around the screw in a range
of predetermined angle and set the rod up thereon. The operating
work using the conventional vertebra fixation apparatus needs
accuracy, because he must correctly grasp the location to install
the pedicle screw and then have to make a hole in vertebra with a
burden on the surgeon. Also, it takes a lot of times to make the
rod based on a curved shape of patient's vertebra and to set the
location of pedicle screw.
To solve the problems of the conventional vertebra fixation
apparatus, the various types of the rods has been provided with
elasticity,
An example of an elastic rod for connecting the pedicle screws is
illustrated in Korean utility model No. 0,338,006. This rod
comprises a rod body 601 and an elastic connection portion 603
formed in the middle of the rod body 601. As shown in FIG. 3, the
elastic rod is in various types, such as a semicircular ring, a
coil spring, a bar type smaller then the diameter of the rod body,
and the like.
These types provide the elastic connection portion for the rod in
order that the rod body can be bent. This structure is capable of
giving fluidity to the rod in a predetermined range between the
pedicle segments. However, the rod structure results in a lose of
the basic function of the spine correction since the elastic
connection portion causes large movement. That is, the rod has to
support and connect the spinal segments. In the above-mentioned
structure, the pieces of the rod body are detachable so that they
are freely movable in a given elastic range. Therefore, the secure
connection between the spinal segments is not achieved.
Also, when the pedicle screws are out of the straight line, the rod
structure has a problem in that it is difficult to connect the rod
to the pedicle screw.
FIG. 4 shows a perspective view of the conventional transverse link
400 for preventing the pedicle from a minute movement.
The transverse link 400 comprises a fixed type housing 410 and a
movable type housing 420 which are respectively hooked on both ends
of the rod 250; a space bar 430 supported on the rod 250; and a set
screw 440 connected with the fixed type housing 410 and the movable
type housing 420 so that the space bar 430 is fixed to the rod
250.
The fixed type housing 410 and the movable type housing 420
respectively include half circle hooks 410a and 420a for connection
on the rod 250; support holes 410b and 420b inserted into the both
ends of the rod 250; screw holes 410c and 420c into which set
screws 440 are inserted.
The hook 410a of the fixed type housing 410 is hooked on the rod
250 and then one end of the space bar 430 is inserted into the
support hole 410b. The hook 420a of the movable type housing 420 is
hooked on the rod 250 and then another end of the space bar 430 is
inserted into the support hole 420b. The set screws 440 are joined
to the screw holes 410c and 420c respectively, for securely
tightening the rod 250 under the space bar 430.
In the structure of the transverse link 400, the inner diameter of
the hook 410a is almost equal to that of the rod 250. Therefore, if
one of the rods 250 is tilted or they are not in parallel, the
transverse link 400 cannot comply with such a declination or
unbalance of the rods 250. In case of the declination or unbalance
of the rods 250, the support holes 410a and 420a of the fixed type
housing 410 and movable type housing 420 are also unbalanced and
thus the space bar 430 cannot be inserted into the support holes
410b and 420b. If strength is put on the space bar 430 for fixation
on the support holes 410b and 420b, the position of the movable
type housing 420 may be wrenched and distorted so that the rod 250
may be separated from the hook 420a of the movable type housing
420. In this case, even if the set screw 440 is joined to the screw
hole 430, it is impossible to securely support the space bar 430
upon the rod 250. This problem in the transverse link 400 requires
to take a long time for an operation on the surgery. In case where
it is difficult to assemble the transverse link 400, it may be
omitted; however, this will cause a defect of the surgery.
SUMMARY OF THE INVENTION
To solve the problems, a primary object of the present invention is
to provide a spinal fixation apparatus which can easily and simply
achieve a connection between a pedicle screw and a rod, even if it
is slightly out of alignment of the pedicle screws during surgery,
by deforming the shape and length of each of the rods and the
transverse link which are made from a shape memory alloy of which
the shape is changed at a specific temperature.
Another object of the present invention is to provide a spinal
fixation apparatus which has a strength enough to correct the spine
during the restoration from an elastic force so that the spinal
fixation apparatus gives flexible behavior to corrected vertebral
segments.
Further, another object of the present invention is to provide a
staple type rod which is made from a shape memory alloy. The staple
type rod of the present invention can easily and simply perform an
operation of the vertebra correction and reduce the number of
parts, being implanted directly into selected vertebra without a
pedicle screw.
In accordance with one aspect of the present invention, there are
provided a spinal fixation apparatus comprising: a plurality of
pedicle screws, each of which has a head formed at a top portion
thereof and a thread formed below the head to be implanted into a
pedicle of a vertebra, wherein the head has a reception cavity and
at least one rod groove on a bottom surface of the reception
cavity; a pair of rods connected to the pedicle screws for
preventing a movement of the vertebra, wherein the rods has an
elasticity section therein and are mounted on the rod groove in the
reception cavity; at least one transverse link which has an
elasticity section in a straight member and hooks extended from
both ends of the straight member for rigidly holding the pair of
rods; and a plurality of set screws, each of which is rigidly
inserted into the reception cavity of the head, preventing a
movement of the rod, wherein the rods and the transverse link are
made from a shape memory alloy which can be deformed at a
predetermined temperature.
In accordance with another aspect of the present invention, there
are provided a spinal fixation apparatus comprising: a plurality of
pedicle screws, each of which has a head formed at a top portion
thereof and a thread formed below the head to be implanted into a
pedicle of a vertebra, wherein the head has a first rod groove
formed in a bottom surface of the head; a plurality of head caps
for covering the head of the pedicle screw, wherein the head cap
has a second rod groove formed on an inner surface thereof; a pair
of rods surrounded by the first rod groove of the head and the
second rod groove of the head cap, preventing a movement of the
vertebra, wherein the rods has an elasticity section therein; at
least one transverse link which has an elasticity section in a
straight member and hooks extended from both ends of the straight
member for rigidly holding the pair of rods; and a plurality of
fixing means, each of which tightens the head cap to the head of
the pedicle screw, being inserted into the reception cavity of the
head of the pedicle screws for preventing a movement of the rod,
wherein the rods and the transverse link are made from a shape
memory alloy which can be deformed at a predetermined
temperature.
In accordance with further another aspect of the present invention,
there are provided a spinal fixation apparatus comprising: a
plurality of pedicle screws, each of which has a head formed at a
top portion thereof and a thread formed below the head to be
implanted into a pedicle of a vertebra, wherein the head has a
reception cavity and two parallel rod grooves in a bottom surface
of the reception cavity; a pair of rods connected to the pedicle
screws for preventing a movement of the vertebra, wherein the rod
is made of shape memory alloy which can be transformed in
designated temperature and wherein the rods includes: 1) a straight
bar placed in line with a center of the heads; 2) an elastic
section formed in the straight bar; and 3) support bars having
bending portions extended from both ends of the straight bar and
bent along an outer surface of the head and line portions extended
from both ends of the bending portions and put in the rod grooves,
and a plurality of set members, each of which is inserted into the
reception cavity of the head of the pedicle screws for preventing a
movement of the rods.
In accordance with still another aspect of the present invention,
there are provided a spinal fixation apparatus comprising: a
plurality of pedicle screws, each of which has a head formed at a
top portion thereof, and a thread formed below the head to be
implanted into a pedicle of a vertebra, wherein the head has at
least one circular groove on an outer surface thereof; and a pair
of rods connected to the pedicle screws for preventing a movement
of the vertebra, wherein each of the rods has a straight bar placed
in line with a center line of the heads, an elastic section formed
in the straight bar, support rings wound on the circular grooves of
the heads, wherein the rods are made from a shape memory alloy
which can be deformed at a predetermined temperature.
In accordance with still another aspect of the present invention,
there are provided a spinal fixation apparatus comprising: a
plurality of pedicle screws, each of which has a head formed at a
top portion thereof, and a thread formed below the head to be
implanted into a pedicle of a vertebra, wherein the head has a
horizontal opening passing through a head body and a perpendicular
thread hole to receive a fixing means; a pair of rods connected to
the pedicle screws for preventing a movement of the vertebra,
wherein the rods has a straight bar, and hooks extended from both
ends of the straight bar and bent to be inserted into the
horizontal opening, wherein the rods are made from a shape memory
alloy which can be deformed at a predetermined temperature; and a
plurality of fixing means for preventing a movement of the rod
through the perpendicular thread hole of the head.
In accordance with still another aspect of the present invention,
there are provided a spinal fixation apparatus comprising: a
plurality of pedicle screws, each of which has a head formed at a
top portion thereof and a thread formed below the head to be
implanted into a pedicle of a vertebra, wherein the head has a
reception cavity and two parallel rod grooves in a bottom surface
of the reception cavity; a pair of rods connected to the pedicle
screws for preventing a movement of the vertebra, wherein each of
the rods has a "U" shape and wherein the rods are made from a shape
memory alloy which can be deformed at a predetermined temperature;
and a plurality of set members, each of which is inserted into the
reception cavity of the head of the pedicle screws for preventing a
movement of the rod.
In accordance with still another aspect of the present invention,
there are provided a spinal fixation apparatus comprising: at least
one pedicle screw which has a head at a top portion thereof and a
thread formed below the head to be implanted into a pedicle of a
vertebra, wherein the head has a reception cavity and two parallel
sockets formed in a bottom of the reception cavity; a pair of
staple rods connected to the pedicle screws for preventing a
movement of the vertebra, wherein one side of each of the rods is
directly implanted into a pedicle of the vertebra and the other
side is inserted into one of the sockets; and at least one set
member which is inserted into the reception cavity of the head of
the pedicle screws for preventing a movement of the rod.
In accordance with still another aspect of the present invention,
there are provided a spinal fixation apparatus comprising: at least
one staple rods each of which has a bridge member for providing a
space between a selected vertebra and an adjacent vertebra, an
elastic section formed in the bridge member and a spike member to
be implanted into the pedicle of a vertebra, wherein the spike
member is downwardly extended from both ends of the bridge member,
wherein the rod is made of shape memory alloy which can be deformed
at a predetermined temperature.
In accordance with still another aspect of the present invention,
there are provided a spinal fixation apparatus comprising: a
plurality of pedicle screws having a head part; and a pair of rods
for connecting the pedicle screws, wherein the rods are in a first
structure at a first temperature range and are in a second
structure at a second temperature range, wherein the second
structure is a memorized shape of a shape memory alloy, and wherein
the rods provide a handling margin in the first structure so that
the rods of the memorized shape are more tight than those of the
first structure, wherein the head part has a fixating means for
securely fixing the rod and end parts of the rod are joined to the
fixating means.
In accordance with still another aspect of the present invention, a
spinal fixation apparatus comprising: first and second pedicle
screw arrays perpendicularly arranged, substantially being in
parallel to each other, wherein each of the first and second
pedicle screw arrays includes: a) a plurality of pedicle screws
joined to vertebras of human spine, each pedicle screw includes: 1)
a head having a plurality of reception means; and 2) a male thread
formed on a leg part to be implanted into the vertebras; and b)
first and second rod arrays respectively connected the first and
second pedicle screw arrays, wherein each of the first and second
rod arrays includes a plurality of segment rods and wherein an end
of each the segment rod is safely secured to one of the plurality
of reception means, wherein the segment rods are a shape memory
alloy.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects and benefits of the present invention will become
apparent upon consideration of the following written description
taken in conjunction with the following figures:
FIG. 1 is a perspective view illustrating a conventional spine
fixation apparatus;
FIG. 2 is a perspective view illustrating a conventional spine
fixation apparatus applied to the lumbar spine;
FIG. 3 is a plan view illustrating various forms of conventional
rods;
FIG. 4 is a perspective view illustrating a conventional transverse
link applied to the rods;
FIG. 5 is a perspective view illustrating a spine fixation
apparatus according to a first embodiment of the present
invention;
FIG. 6 is a perspective view illustrating an assembly of the spine
fixation apparatus shown in FIG. 5;
FIG. 7 is a cross-section view taken along A-A line shown in FIG.
6;
FIG. 8 is a plan view illustrating another form of the rod in the
first embodiment of the present invention;
FIG. 9 is a sectional view illustrating a pedicle screw in the
first embodiment of the present invention;
FIG. 10 is a plan view illustrating a serial connection of the rods
and the pedicle screws shown in FIG. 9;
FIG. 11 is a perspective view illustrating a transverse link
applied to the rods according to a first embodiment of the present
invention;
FIG. 12 is a front view illustrating a connection between the
transverse link and rods;
FIG. 13a is a perspective view illustrating another form of the
rod;
FIG. 13b is a plan view illustrating another form of the rod;
FIG. 14 is a perspective view illustrating a connection between the
transverse links to a head of the pedicle screw;
FIG. 15 is a front view illustrating a spine fixation apparatus
according to a second embodiment of the present invention;
FIG. 16 is a perspective view illustrating a spine fixation
apparatus according to a third embodiment of the present
invention;
FIG. 17 is a plan view illustrating a serial connection the rods to
a head of a pedicle screw shown in FIG. 16;
FIG. 18 is a perspective view illustrating a spine fixation
apparatus according to a fourth embodiment of the present
invention;
FIG. 19 is a perspective view illustrating a serial connection the
rods to a head of a pedicle screw shown in FIG. 18;
FIG. 20 is a plan view illustrating an assembly of spine fixation
apparatus shown in FIG. 18;
FIG. 21 is a perspective view illustrating a spine fixation
apparatus according to a fifth embodiment of the present
invention;
FIGS. 22a and 22b are perspective views illustrating a spine
fixation apparatus according to a sixth embodiment of the present
invention;
FIG. 23 is a perspective view illustrating a spine fixation
apparatus according to a seventh embodiment of the present
invention;
FIG. 24 is a perspective view illustrating a staple rod in the
seventh embodiment of the present invention;
FIG. 25 is plan view illustrating a pedicle screw in the seventh
embodiment of the present invention;
FIG. 26 is a perspective view illustrating a serial connection of
the stapling rods to a head of the pedicle screw shown in FIG.
23;
FIG. 27 is a perspective view illustrating a spine fixation
apparatus according to an eight embodiment of the present
invention;
FIG. 28 is a perspective view illustrating another form of the
staple rod.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, the present invention will be described in detail
referring to the accompanying drawings. A spinal fixation apparatus
according to the present invention can easily correct injured
spines by using rods and transverse links which are made from a
shape memory alloy. In particular, the rods and transverse links
are made out of Nitinol alloy (Ni--Ti alloy) which has a
superelastic characteristic.
A first embodiment will be described in detail referring to FIGS. 5
to 14.
According to the first embodiment of present invention, the spinal
fixation apparatus includes a plurality of pedicle screws 1
implanted into the patient's vertebra; a pair of rods 2 located in
both laterals of the spine and connected to the pedicle screws for
preventing a movement of the vertebra; and a number of transverse
links 3 for providing space between the rods.
Referring now to FIGS. 5 to 7, the pedicle screw 1 comprises a head
11 formed at a top portion thereof and a thread 13 formed below the
head to be implanted into the vertebra. The head 1 has a reception
cavity 11a to receive the rod 2 and at least one rod groove 12 at
the bottom of the reception cavity 11a. A diameter of the rod
groove 12 corresponds to that of the rod 2.
The rod 2 has a rod body 15 which is bent and then has a hook shape
at both ends thereof and the rod 2 has an elasticity section 16
formed in the middle of the rod body 15 to generate an elastic
force corresponding to a shock which is inflicted on the patient's
vertebra.
The elasticity section 16 is made of a coil spring. The coil spring
is equal to the rod body 15 in their diameters. Another form of the
elasticity section 16 is shown in a wave shape as shown in FIG. 8.
The diameter of the rod is approximately in a range of 2 to 7 mm
and it can be adjusted on a basis of unit diameter of 0.5 mm.
The elasticity section 16 serves as a buffer between spinal
segments when the pedicle screw 1 is fused together with the spine.
That is, when patients bends or wrenches his waist or an shock is
inflicted on his waist, the elasticity section 16 can alleviate
stimuli which are caused by patients' activities or the external
shock.
A set screw 17 is inserted into the reception cavity 11a of the
head 11 of the pedicle screws 1 for preventing a movement of the
rod 2. The set screw 17 has an outer thread 17a for securely
tightening the rod 2 and a recess 17b having a hexagonal
cross-section view on the upper portion thereof so that the set
screw 17 is inserted into the reception cavity 11a of the head 11.
The length of the set screw 17 should be short enough not to
protrude from the upper surface of the reception cavity 11a of the
head 11.
The reception cavity 11a of the head 11 also has an inner thread
11b to be joined to the outer thread 17a of the set screw 17.
The head 11 of the pedicle screw 1 has a rod fixing recess 14 for
tightening an end of the rod 2. The rod 2 is inserted into the
reception cavity 11a and is put into the rod groove 12 as the end
of the rod is tightly inserted into the rod fixing recess 14.
The rod fixing recess 14 and the rod 2 have the same diameter or
the diameter of the rod fixing recess 14 is slightly larger than
that of the rod 2.
A head cap 18 can be adopted on the upper portion of the head 11 to
eliminate the change from a misaligned fixation of the set screw
17. Since the head cap 18 provides an additional support to improve
the rod holding power, this can be used as an additional rod such
as a fastening element. The head cap 18 is additionally set as
needed, not essential.
The head 11 of the pedicle screw 1 is able to have two rod grooves
12 and 12' and two rod fixing recess 14, 14', as shown in FIG. 9.
According to this structure, it is able to serially set the rods 2
without using an additional connector by inserting the rods 2 and
2' into the rod grooves 12 and 12' alternately, as shown in FIG.
10.
The first embodiment of the present invention is restricted within
the above structure. For example, the rod can be formed in a
straight bar shape or a right angle bar shape which is
perpendicular to both ends of the rod body. In such a modified rod,
the structure of the pedicle screw 1 is formed with a single rod
groove without the rod fixing recess 14. Besides, it may be
employed in different structures of the pedicle screw corresponding
to the modified rod. Furthermore, the modified rod 2 is securely
fixed by the set screw 17 within the reception cavity 11a of the
head 11.
A transverse link 3 will be described in detail referring to FIGS.
11 and 12.
The transverse link 3 includes one straight member 31 and two hooks
32 which are respectively extended and bent from both ends of the
straight member 31. The transverse link 3 is formed in a
rectangular plate. The length of the transverse link 3 is
approximately in a range of 20 to 80 mm and it can be adjusted on a
basis of unit length of 2 mm. As shown in FIG. 12, the transverse
link 3 keeps a space between the rods 2 and 2' by grasping the rods
2 and 2' through the hooks 32. Here, the transverse link 3 of a
plate shape has strength to maintain the space between the rods 2
and 2' even if an external force is applied to the rods 2 and 2'
and the rods 2 and 2' are then wrenched.
FIG. 13a and FIG. 13b are views illustrating transverse links which
are different from that of FIG. 11. That is, an elasticity section
33 is formed in the middle of a straight member 31. The elasticity
section 33 has a coil spring as shown in FIG. 13a or a wave shape
as shown in FIG. 13b. The elasticity section 33 of the transverse
link 3 absorbs a load which is applied to the rod 2.
FIG. 14 illustrates an S-shaped transverse link 3 which is
different from that of FIG. 11.
The S-shaped transverse link 3 includes one bending member 36 and
two hooks 32 which are horizontally extended and bent from both
ends of the bending member 36 for holding the head 11 of the
pedicle screw 1. A slit 25 is provided on the circumference of the
head 11 of the pedicle screw 1 in order to insert the hooks 32 of
the S-shaped transverse link 3 into the head 11.
The above-mentioned rods 2 and 2' and transverse links 3 in the
first embodiment of present invention are made from a shape memory
alloy causing deformation at a specific temperature.
The rods 2 and 2' and the transverse links 3 have a temperature
characteristic that they are in a martensite phase at a temperature
of +10.degree. C. and below and in an austenite phase at a
temperature of more than +35.degree. C. to return back to a
memorized original shape. In particular, the deformed shape is kept
unchanged up to +26.degree. C. and the memorized shape is gradually
restored by a heat treatment up to +35.degree. C.
The rods 2 and 2' and the transverse link 3 are obtained by
performing a heat treatment at a temperature of 650.degree. C. to
750.degree. C. for one hour or so, after forming the hooks and
elastic section at both ends and the middle section of the shape
memory material, respectively. Thus, the rods 2 and 2' and the
transverse link 3 have a deforming characteristic at a specific
temperature.
Hereinafter, the installation procedures of according to the first
embodiment of the present invention will be described in
detail.
The pedicle screws 1 are implanted into a selected pedicle of the
vertebras in a predetermined angle and depth. At this time, that is
not considered configuration of screws that are not well aligned in
general. It lengthens the elastic section 16 of the rod 2 by
deforming the rod 2 at a temperature of +10.degree. C. and below so
that the rod 2 is easily set into the reception cavity 11a of the
head 11 of the pedicle screw 1, before the rod 2 is inserted into
the reception cavity 11a of head 11 for coupling the rod 2 to the
plurality of the screws 1. Then, the end of the rod 2 of the hook
shape is inserted into the rod fixing recess 14, while a deformed
straight member (the rod body 15) of the rod 2 is inserted to the
rod groove 12 which is formed in the bottom of the reception cavity
11a of head 11. The outer thread 17a of the set screw 17 is
downwardly joined to the reception cavity 11a of the head 11 so
that the set screw 17 is tightly fixed to the inner thread 11b of
the reception cavity 11a using a wrench tool. The rod 2 is pressed
by the set screw 17 and the rod 2 is securely and rigidly fixed to
the pedicle screw 1.
After the installation of the rods 2, a heat treatment is applied
to the rod 2 at a temperature of more than +35.degree. C. using a
surgical heating source. And thus, the lengthened elastic section
16 of the rod 2 is shrunk and returns back to the memorized
original shape in the transforming austenite phase. At this time,
the end of the hook-shaped rod is rigidly fix to the rod fixing
recess 14 of the head 11 while the rode 2 is returning back to the
memorized original shape. Thus, both ends of the rod 2 are fixed to
the rod fixing recess 14 of the head 11 without any separation.
According to the above mentioned description, although the pedicle
screws are not well aligned with others, the rode can be easily and
simply connected to the pedicle screw 1 because the rod 2 can be
freely bent toward the pedicle screw 1. In additional, the rod 2
provides a movement of between the spinal segments through the
superelastic action of the elastic section 16 when the patients
bend or wrench his back, after the spine fusion.
In the installing procedures of the rods 2, when the rods 2 and 2'
are respectively coupled to the rod grooves 12, the pedicle screw 1
having the two rod grooves 12 and 12 are used. That is, the rods 2
and 2' are respectively and alternately set to the rod grooves 12
and 12' positioned in the reception cavity 11a, as shown in FIG.
10. Therefore, in case that the pedicle screw 1 having two rod
grooves 12 and 12' are used, it is not necessary to take an
additional connector for a serial connection.
Next, an installation procedure of the transverse link 3 will be
described in detail.
After coupling the rods 2 and 2' to the pedicle screws 1, the
transverse link 3 is hung on a pair of the rods 2 to provide a
space between the two rods 2. The installing work of the transverse
link 3 is taken in the same manner as it done in the
above-mentioned rod installation procedure. That is, it lengthens a
body 31 or widens a space of the hooks 32 thereof, by deforming the
transverse link 3 at a temperature of +10.degree. C. and below. The
deformed hook 32 of the transverse link 3 is inserted into the
outer surface of the rod 2. In case of the S-shaped transverse
link, it is inserted into a slit 25 of the head 11. After the
installation of the transverse link 3, it returns back to the
memorized original shape, being transformed to the austenite phase
through the heat treatment at a temperature of more than
+35.degree. C. so that the transverse link 3 is rigidly fixed on
the rod and, in case of the S-shaped transverse link 3, it is fixed
on the slit 25 of the pedicle screw 1.
Thus, in case of the above-mentioned structure of the transverse
link 3, it easily holds the rod 2 even if a space between the rods
2 and 2' is not in parallel.
A second embodiment of the present invention will be described in
detail referring to FIG. 15 and the same reference numerals denote
the same elements as illustrated in the first embodiment of the
present invention.
In the second embodiment, the head 11 of the pedicle screw 1 is
formed with a pair of first rod grooves 21 and 21' to locate the
rod 2 on an upper portion thereof. Also, a pair of rod inserting
recesses 22 and 22' are respectively formed below the rod grooves
21 and 21' and the rod inserting recesses 22 and 22' are positioned
in the same axis of the rod grooves 21 and 21', respectively. A
female thread 23 is formed on an inner surface of the head 11 at a
predetermined depth.
A head cap 20 is provided on the upper portion of the head 11 and
the head cap 20 has a pair of second rod grooves 24 and 24'
corresponding the first rod grooves 21 and 21'. A fixing screw 25
is joined to the female thread 23 passing through the head cap 20
so that the head 11 is strongly fixed to the head cap 20.
A diameter of the first rod grooves 21 and 21' and the second rod
grooves 24 and 24' is correspondent to that of the rods 2 and 2'.
And the rod inserting grooves 22, 22' have the same or slightly
large diameter than that of the rod 2.
If only one of the first rod grooves 21 and 21' is provided, two
female threads may be positioned at both sides of the first rod
groove. If two rod grooves are provided, one female thread may be
positioned in the middle of the first rod grooves 21 and 21'. In
this drawing, the pair of the first rod grooves 21 and 21' are
shown. These two grooves are required to serially and alternately
set the two rods 2 and 2' on the first rod grooves 21 and 21'.
A third to eight embodiments of the present invention will be
described in detail referring to FIGS. 16 to 28.
A rod, a staple rod and a middle connection rod in the these
embodiments are made from a shape memory alloy which is in a
martensite phase at a temperature of +10.degree. C. and below and
in an austenite phase at a temperature of more than +35.degree. C.
to return back to the memorized original shape. The shape memory
alloy of these embodiments undergoes a preliminary deformation at a
temperature of +10.degree. C. and below. A deformed shape is kept
unchanged up to temperature +26.degree. C. A shape restoration is
occurs under the heating up to +35.degree. C.
A third embodiment of the present invention will be described in
detail referring to FIGS. 16 and 17.
A plurality of pedicle screws 40 according to this embodiment
comprises; a head formed at a top portion thereof, wherein the head
has a reception cavity 41a and two parallel rod grooves 42 and 42'
in bottom surface of the reception cavity 41a; and a thread 43
formed below the head to be implanted into a pedicle of the
vertebra.
Two parallel rod grooves 42 and 42' in the reception cavity 41a
contributes to a connection of the rods 50 and the pedicle screws
40 without an additional connector. Here, the rod grooves 42, 42'
have a diameter equivalent to the rod 50.
A set screw 44 is inserted into the reception cavity 41a of the
head 41 of the pedicle screws 40 for preventing a movement of the
rod 50. In order to securely tighten the rod 50, the set screw 44
has an outer thread 44a and a recess 44b which has a hexagonal
cross-section view in the reception cavity 41a of the head 41. The
length of the set screw 44 should be short enough not to protrude
from the upper surface of the reception cavity 41a of the head 41.
The reception cavity 41a of the head 41 has an inner thread 41b to
be joined to the outer thread 44a of the set screw 44.
A head cap 45 can be adopted on the upper portion of the head 41 to
eliminate the change from a misaligned fixation of the set screw
44. The head cap 45 serves as an additional supporter to improve
the rod holding power using an additional rod-fastening
element.
A pair of rods 50 according to this embodiment comprises; a
straight bar 51 placed at the center line of the heads; an elastic
section 52 formed in the middle of the straight bar 51 to generate
an elastic force for absorbing a shock which is inflicted on the
patient's vertebra; and a support bar 53 extended from both ends of
the straight bar 51 to be put in one of the rod grooves 42 and
42'.
The diameter of the rod is approximately in a range of 2 to 7 mm
and it can be adjusted on a basis of unit diameter of 0.5 mm.
The elasticity section 52 is similar to a coil spring. The coil
spring is equal to the straight bar 51 in their diameters. The
elasticity section 52 can has a wave shape as another form.
The support bar 53 have a line portion 53a, which can be put on one
of the rod grooves 42a and 42', and a bending portion 53b which is
extend from both ends of the straight bar 51 and curved along the
outer surface of the head 41.
The straight bar 51 of the rod 50 is positioned on the central axis
of the head 41 by the shape of the support bar 53.
One of the two support bars 53 is opposite to the other in the same
head 41; however, the two support bars 53 can be in a reverse phase
to each other, even if it is not shown in the drawings. That is,
the rod 50 can be serially and alternately connected to the pedicle
screw 40 with the support bar 53 of which the bending portions 53b
are reversibly positioned and are curved along the outer surface of
the heads 41.
Referring to FIG. 17, the support bars 53 at both sides of the rod
50 are respectively put into the rod grooves 42 and 42'. Also, the
set screws 44 are coupled to the inner threaded 41b of the
reception cavity 41a of the head 41, being rigidly fixed to the rod
50.
A forth embodiment of the present invention will be described in
detail referring to FIGS. 18 to 20.
Referring now to FIG. 18, it comprises only a plurality of pedicle
screws 60 and a rod 70.
The pedicle screws 60 includes a head 61 formed at the top portion
thereof and a thread 62 formed below the head 61. The head 61 has
first and second circular grooves 61a and 61a' formed in an outer
surface thereof.
The rod 70 includes two straight bars 71 and 71' placed at the
center line of the head 61 of the pedicle screw 60, an elastic
section 72 formed in a type of wave between the two straight bars
71 and 71', and support rings 73 and 73' respectively extended from
both ends of the straight bars 71 and 71' to be inserted into one
of the first and second circular grooves 61a, 61a'.
The support rings 73 and 73' of the rod 70 are in reverse phase to
each other; however, they may be opposite to each other in the same
head 61, even if it is not shown in the drawings.
Referring now to FIGS. 19 and 20, the rods 70 are serially and
alternately connected to the plurality of circular grooves 61a and
61a' of the heads 61 of the pedicle screws 60, using the above
support rings 73 and 73'.
A fifth embodiment of the present invention will be described in
detail referring to FIG. 21.
Referring now to FIG. 21, the fifth embodiment comprises a
plurality of pedicle screws 80 have a head 81, which is formed at
the top portion thereof and has a cylindrical type block, and a
thread 82 formed below the head 81. The head 81 has an opening 81a
horizontally passing through the cylindrical type block to receive
both ends of a rod 90 and a thread hole 81b which is upwardly
formed and is perpendicular to the opening 81a. The thread hole 81b
of the head 81 is joined to a bolt 83 in order to tight the rod
90.
The rod 90 has a straight bar 91 and hooks 92 and 92' which are
roundly extended from both ends of the straight bar 91 to be
inserted to the opening 81a. The straight bar 91 can be provided
with an elastic section in the middle of the rod 90.
Hereinafter, the installation procedure of the rod 90 will be
described in detail.
In this embodiment, when the rod 90 is coupled to the pedicle screw
80, the roundly curved hooks 92 of the rod 90 is deformed to a
straight bar shape at a temperature +10.degree. C. and below. On
the other hand, the straight bar shaped hooks 92 of the rod 90 is
inserted to the opening 81a. Thereafter, a heat treatment is
applied to the rod 90 at a temperature of more than +35.degree. C.
the deformed hooks 92 of the rod 90 are returned back to the
memorized original shape and is rigidly fixed to the head 81. After
the rod 90 is inserted into the pedicle screw 80, the bolt 83 is
joined to the thread hole 81b of the head 81 for tightening the rod
90 to the pedicle screw 80.
A sixth embodiment of the present invention will be described in
detail referring to FIG. 22.
This sixth embodiment makes the connecting work simple, by simply
coupling the rod to the pedicle screw after a plurality of the
pedicle screws are installed in the pedicles of the vertebras.
Referring now to FIG. 22a, the detailed description of the pedicle
screw will be omitted because the structure of the pedicle screw 40
is the same as that in the above-mentioned third embodiment. The
same reference numerals denote the same elements as illustrated in
the third embodiment.
A rod 100 of this sixth embodiment is formed in "U" shape. The
U-shaped rod 100 is put into the rod grooves 42 and 42' of the head
41, after the pedicle screws 40 is inserted into pedicle of the
vertebras. The connecting work of the rod 100 is achieved by
tightening the set screw 44 to the reception cavity 41a of the head
41 in order to fix the rod 100 to the pedicle screw 40. If the
pedicle screws 40 are not well aligned, the U-shaped rod 100 may be
deformed to comply with the misaligned pedicle screw 40.
Accordingly, the deformed rod 100 is easily positioned in the rod
grooves 42 and 42' of the reception cavity 41a of the head 41. The
deformed rod 100 is returned back to the original shape according
to a memorized shape of the rod 100, thereby correcting a position
of the misaligned pedicle screw 40.
The U-shaped rods 100 can be replaced with a straight bar type rods
101 and 101' as shown in FIG. 22b. An elastic section 102 is
provided in the middle of the straight rods 101 and 101'. The
straight rods 101 and 101' are respectively and alternately set to
the rod grooves 42 and 42' which are positioned in the reception
cavity 41a. Therefore, in case that the straight rods 101 and 101'
having the elastic section 102 are used, it is not necessary to
have an additional connector for such a serial connection.
A seventh embodiment of the present invention will be described in
detail referring to FIGS. 23 to 26.
Referring now to FIGS. 23 to 25, the seventh embodiment comprises
at least one pedicle screw 110, a pair of stapling rods 120, and a
middle connecting rod 140.
Referring now to FIG. 25, the pedicle screw 110 has a head 111 at
the top portion thereof and a thread 113 formed below the head 111
to be implanted into the pedicle of the vertebra, wherein the head
111 has a reception cavityllla and first and second sockets 112 and
112' formed in the bottom surface of a reception cavity 111a.
The rod 120 is formed in a staple structure for preventing a
movement of the vertebra.
One side of the staple rod 120 is directly implanted into the
pedicle of the vertebra and other side thereof is inserted into one
of the sockets 112 and 112'.
The middle connecting rod 140 is employed for serially connecting
the staple rod 120 to the pedicle screw 110 by inserting both ends
thereof to the sockets 112 and 112' of the head 111,
respectively.
Referring to FIG. 24, the staple rod 120 has a first bridge 121 for
providing a space between selected vertebra and adjacent vertebra,
an elastic section 126 formed in the middle of the first bridge
121, a spike 122 downwardly extended from one end of the first
bridge 121 to be implanted directly into the pedicle of the
vertebra, and a first connecting pole 123 downwardly extended from
the other end of the first bridge 121 to be fixed to the pedicle
screws 110. The length of the first connecting pole 123 is shorter
than the depth of the reception cavity 111a of the head 111 so that
the first connecting pole 123 is inserted into the socket 112 of
the pedicle screw 110. The spike 122 has a plurality of scarred
regions 125 for preventing the spike 122 from being detached from
the pedicle of the vertebra. The scarred regions 125 may be formed
by an electro discharge machine. The diameter of the staple rod 120
is approximately in a range of 2 to 7 mm and it can be adjusted on
a basis of unit diameter of 0.5 mm.
Once a spinal fusion has been finished, the staple rod 120 is not
separated from the vertebra because the scarred regions 125 are
buried in the vertebra.
According to the embodiment of the present invention, it is able to
make a connection among three adjacent vertebras, using two staple
rods 120 and one pedicle screw 110.
The middle connecting rod 140 has a second bridge 141 for providing
a space between the pedicle screws 110, an elastic section 146
formed in the middle of the second bridge 141, and second
connecting poles 142 downwardly extended from both ends of the
second bridge 141, wherein the length of the second connecting
poles 142 is shorter than the depth of the reception cavityllla of
the head 111. The reason why is that a volume should be prepared
for the insertion of a fixing member such as a set screw.
The first connecting pole 123 of the staple rod 120 and the second
connecting poles 142 are substantially equal to each other. In the
serial connection, one of the second connecting poles 142 extended
at both ends of the middle connecting rod 140 is inserted into the
socket 112 of head 111 of the pedicle screw 110 and the other is
inserted into the socket 112' of head 111' of the adjacent pedicle
screw 110'.
The elastic sections 126 and 146 can be made up of a coil spring or
a wave shape element. The diameter of each elastic sections 126 and
146 is substantially the same as that of first and second bridge
121 and 141.
In this embodiment, at least one set screw 130 is joined to the
reception cavity 111a of the head 111 of the pedicle screws 110 for
preventing a movement of the staple rod 120.
Likewise, in this embodiment, at least one head cap 131 is adopted
to the upper surface of the head 111. The head cap 131 is provided
to improve holding power of the staple rod 120 without an
additional rod such as a fastening element.
Hereinafter, an installation procedure of the staple rod 120 among
the first to fourth vertebras will described in detail.
Referring to FIGS. 23 and 26, the first and second pedicle screws
110 and 110' are implanted into second and third middle vertebras,
respectively. The first connecting pole 123 of the first staple rod
120 is inserted into one of the sockets 112 and 112' of the first
pedicle screw 110 and another connecting bar (123') of the second
staple rod 120' is inserted into the socket 112'' of the second
pedicle screw 110'.
The spikes 122 and 122' of the first and second staple rods 120 and
120' are implanted into the first vertebra and forth vertebra,
respectively. The two second connecting poles 142 at both sides of
the middle connecting rod 140 are inserted into the sockets 112' an
122'' of the first and second pedicle screws 110 and 110,
respectively.
After the installation of the staple rods 120 and 120' and the
middle connecting rod 140, the outer thread 130a of the set screw
130 is joined to the reception cavity 110a of the head 110 and the
set screw 130 is then joined to the inner thread 110b of the
reception cavity 110a by a wrench tool. Accordingly, the staple rod
120 and the middle connecting rod 140 are simultaneously pressed by
the set screw 130 so that the staple rod 120 and the middle
connecting rod 140 are securely and rigidly fixed in the pedicle
screw 110. Although the pedicle screws 110 and 110' are not well
aligned, the staple rods 120 are easily and simply connected to the
pedicle screw 110. This can be further achieved by the deformation
of the staple rods 120 and the middle connecting rod 140.
Before the first connecting poles 123 and 123' of the first and
second staple rods 120, 120' are inserted into the sockets 112,
112' of the head 111, the staple rod 120 will be deformed at a
phase transformation point (+10.degree. C. and below) on condition
that one end of the first staple rod 120 is optimally connected to
the socket 112 of the head 111. Further, the spikes 122 and 122' of
the deformed first and second staple rods 120 and 120' are
implanted into bores of the vertebras. Also, the first connecting
poles 123 and 123' of the first and second deformed staple rods 120
and 120' are joined to the sockets 112 and 112' of the head 111.
Finally, the rod connection is completed among the pedicle screws
110 and 110', the staple rods 120 and 120' and the middle
connecting rod 140.
Next, a heat treatment is applied to the staple rods 120 and the
middle connecting rod 140 at a restoration point (+35.degree. C.
and over), using a surgical tool to have a heating source. The
lengthened elastic sections 126 and 146 are returned back to the
memorized original shape and are transformed to an austenite
phase.
At this time, the first and second connecting poles 123 and 142,
the staple rod 120 and the middle connecting rod 140 is rigidly
fixed to the sockets 112 and 112' of the head 110, during the
restoration to the memorized original shape.
According to this embodiment, a movement between spinal segments is
given by the superelastic action of the elastic section 126 and
146, which are respectively formed in the staple rod 120 and the
middle connecting rod 140, when the patients bend or wrench his
back after the spine fusion.
According to the above-mentioned structure of the seventh
embodiment, the first and second staple rods 120 and 120' are
formed in the symmetric structure. Thus, it is necessary to have
four pedicle screws even though all of them are needed in the
conventional spinal fixation system; however, it is necessary to
have only two pedicle screws in the present invention. Therefore,
according to this embodiment, the number of the pedicle screw is
reduced. In particular, in case of the correction of two vertebras,
it may be possible to perform the correcting work of the vertebras
by using only one single staple rod 120 without an additional
pedicle screw. In case of correction of three vertebras, it is
necessary to have only one pedicle screw.
An eighth embodiment of the present invention will be described in
detail referring to FIGS. 27 and 28.
In this embodiment, the staple rod 150 is directly implanted into
the pedicle of the vertebra without any pedicle screw.
Referring now to FIGS. 27 and 28, at least one staple rod 150 is
located at both laterals of the spine.
The staple rod 150 has a bridge 152 for providing a space between a
selected vertebra and an adjacent vertebra, a spike 153 downwardly
extended from both ends of the bridge 152 for implantation into the
pedicle of the vertebra, and an elastic section 154 formed in the
bridge 152.
The elastic section 154 can be made of a coil spring (see FIG. 27)
or a wave shape element or a S-shaped element (see FIG. 28). Also,
The spike 153 has a plurality of scarred regions 155 which prevents
the spike 153 from being detached from the pedicle of the
vertebra.
The scarred regions 125 may be formed by an electro discharge
machine.
Although the preferred embodiments of the invention have been
disclosed for illustrative purposes, those skilled in the art will
appreciate that various modifications, additions and substitutions
are possible, without departing from the scope and spirit of the
invention as disclosed in the accompanying claims.
According to the first to eighth embodiment of the present
invention, the rods and transverse links are made of a shape
memorized Nitinol alloy (Ni--Ti alloy) which has a superelastic
characteristic. Thus, although the pedicle screws are out of
alignment during the surgery, the present invention can easily and
simply make a structural connection between the rods and the
pedicle screws without excessive force on the spine and/or
implants.
In addition, in the present invention, the rods and transverse
links have an elastic section in an optional range thereof. The
elasticity section of the rod allows a delicate movement after the
spinal segments fusion. Thus, it disperses a load, which is put on
the spinal segments which have been fused, through the rods and the
transverse links having super-elasticity. As a result, a burden on
lumbar vertebra is reduced. Also, in case of using the spinal
fixation apparatus of the present invention, it has another effect
on the decrease of a complication that can be caused between an
upper segment and a lower segment.
* * * * *